ThaCivicAssassin

Wow I'm taking notes

RiceKillinSI

To put it simply unless you have a Civic Si, Integra GSR or S2000 which 91 octane is required then you just need to run 87. Anything else is just a waste of money.


Modified by RiceKillinSI at 1:07 AM 7/12/2007

sageuvagony

Don't try running 93 either just cuz it seems cool and good for your car. Things like that bug me. It's like my neighbor who changes his oil on all 3 of his cars every 1000 miles. I see him pretty much every single weekend changing his oil on all 3 cars. WTF. I'm about to take all of that remaining oil and use it for something else...

MidwestCivic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RiceKillinSI &raquo;</TD></TR><TR><TD CLASS="quote">To put it simply unless you have a Civic Si, Integra GSR or S2000 which 91 octane is required then you just need to run 89. Anything else is just a waste of money.</TD></TR></TABLE>


89? are you crazy? 87 nothing more!

MidwestCivic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by slowcivic2k &raquo;</TD></TR><TR><TD CLASS="quote">Octane rating is used to quantify the ability for a fuel to resist detonation, under compression it will detonate at varying rates, lower octane combusts faster, and is the staple for most Honda cars and trucks (Requires 86 Octane)

Running 91 in a car designed for use with 86 with no other modifcations will yield a richer AFR, because the fuel takes longer to combust because timing is not optimized for that fuel, it would combust after TDC, and foul the plugs depending on your engines conditions.

The stoichiometric AFR for Ethanol fuel is 9:1, and the mixture of gas with Ethanol would yield an ideal AFR around 9.8:1 This is because Ethanol contains oxygen in the fuel. E85 has a pump octane of around 116-126 depending on the blends, which can vary because Ethanol absorbs water very easily.

Honda's PCM Short/Long Term Fuel Trims can correct up to 20% in either rich or lean, and will set a system too rich/lean if the long term value exceeds 18% in either direction.

Octane requirements increase as compression and timing increase, as you all should know.

100% clean fuel will ignite, the inperfection in gasoline is Heptane, which has a low self ignition point compared to Octane. (this is how you get varying grades of fuel)</TD></TR></TABLE>

the point being, say your running lean, you cant just fill up with 93 and then start running rich. You need more usable fuel, the 93 will just not ignite and seep down past the rings, contaminating your oil. and i believe its up like 23% +/- 2%

Egezzy

iTrader: (2)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 4thgenx42 &raquo;</TD></TR><TR><TD CLASS="quote">I know from my personal experience of working for SUNOCO that 91+ is the best gas they produce. 93+ is a mixture of cheap and good gas. </TD></TR></TABLE>

what????? how can u say that 91 oct is better than 93?

slowcivic2k

No you don't need more useable fuel, if you misfire (happens whenever combustion is early/late or severely rich/lean) you will get the same result.

If you understand misfire you will know that not all fuel and air is burned, so the unburned air and fuel go into the exhaust, triggering lean on the O2 (O2 meters O2 only, not HC), and the PCM commands a rich condition to compensate (It will do this until the PCM determines that a repetitive misfire is present, at which time the system will default fuel trims. (Because the crank sensor in the distributor is not accurate enough to precisely determine the exact time of the misfire, timing can not be precisely adjusted, which is why we now have Crank Flux Sensors on our oil pump housings.)

No, it is 20% on ALL OBD2 compliant vehicles for short and long term fuel trims, Honda also incorporated many of these features prior to the official mandate in 1996 for OBD2 compliance, so little in the way of revision was needed, as most Honda OBD1 ECU's would be generically compliant in many aspects (but not up to the official standard, such as data streaming, freeze framing, OBD plug type, misfire and component rationality) as all OBD2 running vehicles.

The condition of rich or lean is very minute, and will only result in slightly poorer combustion because a fuel that is more resistant to detonation is going to take more effort to spark, causing later ignition, and light fouling of the plugs, An OBD2 vehicle can correct this by advancing timing to deny the minor retarded misfires. (Because of the newer Crank Flux Sensor, some cars use Ion-Sensing ignition in which is second spark is fired to determine the plasma content of the chamber, to further determine combustion efficiency, this is especially true in Flex-Fuel vehicles in which the actual content of fuel needs to be determined by a device before it can be used, so that it does not misfire if it happens to say, suck up some fuel that is a bit more saturated with Gas/Water than the last fill up so the right AFR is maintained.)

RiceKillinSI

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MidwestCivic &raquo;</TD></TR><TR><TD CLASS="quote">


89? are you crazy? 87 nothing more!</TD></TR></TABLE>

oopps, i ment 87. Post edited

DJP

I do have a Civic Si, so according to you...isn't the 91 octane what i'm supposed to be using?

Mhollaek9

Now I'm confused because Honda recommends Premimum for GSR motor which is 93oct in NY and I know people that run 87 in the GSR and its runs fine none the less 25cents cheaper. If you all say 93 octane is for high compression motors than it must be true that its for stock motors too right?

uneek360

I run 93 on my stock GSR. Nothing Less which i believe is what honda callS for the GSR.

Syndacate

PM sent

FarinaMotorsports

I'm seeing so much misinformation in this thread it's unbelievable. People need to stop trying to appear intelligent by posting BS when they have no idea what they are talking about.

uneek360

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by FarinaMotorsports &raquo;</TD></TR><TR><TD CLASS="quote">I'm seeing so much misinformation in this thread it's unbelievable. People need to stop trying to appear intelligent by posting BS when they have no idea what they are talking about.</TD></TR></TABLE>


Then correct us

FarinaMotorsports

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by uneek360 &raquo;</TD></TR><TR><TD CLASS="quote">


Then correct us </TD></TR></TABLE>

Check page 1, I already posted valid, correct information.

slowcivic2k

Honda defines "Premium Fuel" as 91 octane.

slowcivic2k

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by FarinaMotorsports &raquo;</TD></TR><TR><TD CLASS="quote">I'm seeing so much misinformation in this thread it's unbelievable. People need to stop trying to appear intelligent by posting BS when they have no idea what they are talking about.</TD></TR></TABLE>

I'm sorry you are unable to comprehend what I'm saying, these are very basic concepts.

FarinaMotorsports

Did I specifically call you out? No. Maybe, for some reason, you just felt I was talking to you.

slowcivic2k

well the reply target was me, look at your post header...

RE: slowcivic2k

97civicdx

I use 89 in my 99 SI. No knocks at all and it has 105,000 miles.

slowcivic2k

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 97civicdx &raquo;</TD></TR><TR><TD CLASS="quote">I use 89 in my 99 SI. No knocks at all and it has 105,000 miles.</TD></TR></TABLE>

Honda states in the owners manual to use 91 octane, but that doesn't mean you cant cheat, sometimes you can get away with it, my B16A consistently misfires with 89 at around 6500rpm, so I was not so fortunate.

A GSR requires 91 as well, but almost all of them can get away with running 89.